1. Field of the Invention
The present invention relates to an air conditioner. Particularly, the present invention relates to an air conditioner for a vehicle. More particularly, the present invention relates to a condenser of an air conditioner for a vehicle and the peripheral piping accessories thereof.
2. Description of the Related Art
Conventionally, a general air conditioner for a vehicle comprises a cooling unit that cools a compartment by the adiabatic expansion of a refrigerant compressed by a compressor and a heating unit that heats a compartment by the cooling water that has cooled an engine. In this case, it can be said that energy is utilized effectively and also facilities are utilized effectively because the heat of cooling water that cools an engine, which is the power source of the vehicle itself, is utilized as a heat source for heating.
Moreover, a hot gas cycle, in which a refrigerant compressed adiabatically by a compressor is directly utilized as a heat source for heating, has been proposed recently. In this case, it is possible to assist a hot water heater for heating and to preheat an air-conditioning air by running a cooling unit, which has been used only for cooling, in a hot gas cycle which will be described later and therefore, facilities can be utilized more effectively. On the other hand, from a standpoint of fuel consumption reduction or the like, a demand for a lighter vehicle has been increased recently.
A structure, in which such a hot gas cycle has been included in a conventional air conditioner system for a vehicle, is described with reference to FIG. 1 and FIG. 2. An air conditioner in FIG. 1 and FIG. 2 has a heating and cooling function and comprises a cooling unit 10 and a heating unit (not shown). As the present invention relates to the cooling unit 10, the heating unit is not shown schematically.
During the cooling operation performed by the cooling unit 10 shown in FIG. 1 and FIG. 2, a refrigerant is compressed by a compressor 1 and liquefied through a condenser 2. The liquefied refrigerant is reduced in pressure and expanded adiabatically by a pressure reducing device 3, and then is supplied to an evaporator 4, through a refrigerant pipe 33 and a refrigerant pipe 34 extending from the refrigerant pipe 33, and is then gasified therein. At this time the refrigerant cools the surroundings by absorbing heat from them. The evaporator 4 is contained in an air-conditioning duct and air supplied by an air blower 7 is cooled by exchanging heat with the evaporator 4 while the air passes through the evaporator 4 and is blown into and cools the inside of a vehicle room as air-conditioning air. After this, the refrigerant is drawn in by the compressor 1 and re-circulated.
During heating operation, on the other hand, heating is performed by the heating unit not shown schematically, the engine cooling water heated while it cools the engine (not shown) is supplied to the hot water heater, which is not shown, via a cooling water circulating pipe, air is supplied by the air blower to the hot water heater, contained in the air-conditioning duct, is heated thereby and is blown into the inside of the vehicle room as an air-conditioning air. The cooling water, that has passed through the hot water heater and has been decreased in temperature, circulates into the engine through the cooling-water circulating pipe and is heated again.
Here, it is possible to use a hot gas (HG) cycle in order to assist the hot water heater. The cooling unit 10 is operated simultaneously with the hot water heater during heating operation. A first switching valve 15 is provided between the compressor 1 and the condenser 2, a bypass pipe 18 is further provided between the first switching (stop) valve 15 and the compressor 1, a second switching (stop) valve 16 is provided on the bypass pipe 18, and a refrigerant bypass line is provided by connecting the bypass pipe 18 to the pipe 33 that provides communication between the pressure reducing device 3 and the evaporator 4. The refrigerant is introduced into the pipe 18 and bypasses the condenser 2 and the pressure reducing device 3 by closing the first switching valve 15 to shut off the channel that leads to the condenser 12. The refrigerant is compressed adiabatically by the compressor 1 and its temperature rises. The refrigerant, the temperature of which has risen, is introduced into the evaporator 4, that is, a heat exchanger, and air is heated because it is supplied, to flow through the evaporator 4, by the air blower 7. The air is blown into and heats the inside of a vehicle room. Such a method for using the cooling unit 10 is called the hot gas cycle. It is preferable that the first and second switching valves 15 and 16 are electromagnetic valves.
In the air conditioner that utilizes such a hot gas cycle, a throttle 17 is normally provided within the branch pipe 18 in addition to the second switching valve 16 and a check valve 19 is further arranged within the pipe 33 on the upstream side (on the pressure reducing device 3 side) of the part where the bypass pipe 18 is connected to the piping 33. A pressure sensor 14 may be provided on the upstream side of the first switching valve 15 on a discharge pipe 31 of the compressor 1. When a refrigerant piping circuit is configured in this way, it is preferable that the first switching valve 15, the second switching valve 16, the throttle 17, the check valve 19, the pipe 18, etc. are integrally formed into a unit. By being integrally formed into a unit, the portion including these components can be made more compact and lighter and the numbers of man-hours required in assembling these components can be reduced. As a result, it is possible to reduce the manufacturing and assembling costs. If mass production could be applied, a large economical merit would result by integrally forming these components into a unit.
By integrally forming the piping components into a unit, as described above, it is possible to form a valve unit 5 composed of, for example, the parts enclosed by the alternating long and short dashed line in FIG. 1. However, the valve unit 5 formed integrally into a unit in this way naturally becomes heavier than the individual weight of the switching valves 15 or 16 or the check valve 19. Therefore, where to install the valve unit 5 becomes a problem.
On the other hand, vibration of a vehicle is transmitted to the cooling unit 10 of an air conditioner while the vehicle is traveling because it is used onboard. Various pipes are connected to the condenser 2 that is included in the air conditioner, because of its function, as shown in FIG. 2, and accessories such as a refrigerant tank 21 are further attached thereto. The refrigerant tank 21 is connected to the condenser 2 via a refrigerant pipes and receives the refrigerant from the condenser 2, separates the vapor phase from the liquid phase, and returns the refrigerant vapor to the condenser 2. The condenser 2 is a heat exchanger of a fin tube type and has a thin plane shape as shown in FIG. 2. Moreover, it is generally made of aluminum and the structure thereof is made as thin as possible because of the demand for a lighter vehicle to realize high fuel consumption efficiency, or the like, therefore, the strength thereof satisfies only the minimum requirements.
From the standpoint of the strength of the condenser 2 and the lifetime of components thereof, it should be avoided that the vibrations of the vehicle are directly transmitted to the condenser 2 which has the structure described above. Therefore, the condenser 2 is generally attached to the vehicle body in such a way that vibration insulating materials 26 are arranged at two points, right and left, on the bottom face of the condenser 2 and the condenser 2 is supported through the vibration insulating materials 26, as shown in FIG. 2. Generally, the top face of the condenser 2 is pressed down by pins 27 at two points. The pin 27 may be supported by the vehicle body in such a way that it can move vertically. By configuring this way, the condenser 2 is attached to the vehicle body, without being fixed firmly, in such a way that the vibration of the vehicle body is absorbed and is not transmitted to the condenser 2. The pin 27 may comprise a rubber vibration insulating part internally to realize a vibration insulating effect.
Relating to the arrangement of the condenser 2 described above, it is preferable that the valve unit 5 is arranged near the condenser 2 because the valve unit 5 has many refrigerant pipes through which the valve unit 5 and the condenser 2 are communicated with each other. From this standpoint, it is preferable that the valve unit 5 is attached to fin tubes 28 of the condenser 2. However, the fin tubes 28 do not have enough strength for installation of the valve unit 5 because they are required to be light. Moreover, as the valve unit 5 is heavy, it needs to be installed on a firm structure. It may be an option that the valve unit 5 is installed on the vehicle body near the condenser 2, but in this case, even if a vibration insulating material is provided between itself and the vehicle body, the vibrations of the vehicle body are transmitted to the valve unit 5 and the condenser 2 and they are vibrated individually. Therefore, it is necessary that a pipe 32 and the pipe 33 that connect the valve unit 5 to the condenser 2 are made of a flexible material, or part of them is provided with a flexible material.